This invention relates to a charging device for refuse-burning furnaces, particularly large furnaces, which conveys and supplies the refuse up to a location from which the refuse falls into the combustion chamber.
Urban refuse is collected to an increasing extent in bags of paper and synthetic plastic material. These are convenient and odour-free in use. However, in terms of furnace technology, i.e., when the refuse is to be incinerated, they have the disadvantage that they compact the refuse (see, for example U.S. Pat. No. 3,696,951), make the necessary intermixing difficult and, when charged into the furnace, screen the refuse from immediate contact with the generally preheated combustion air and the radiant heat from the combustion chamber. Plastic sacks fed simultaneously in large numbers into the furnace tend to slide against one another and prevent their being charged in a controlled manner. All of this results in unsatisfactory burning of the refuse.
Disadvantages of this type may be avoided by mechanically crushing the refuse before it is fed into the charging chute but this is often impossible in existing plants for structural reasons and in any case, may be very expensive.
It is also known in the art of charging devices to provide a charging apparatus for furnaces with a charging chute having two walls, one of which is provided with stationary ripping elements (see, for example U.S. Pat. No. 3,696,951) operative to tear up refuse bags inserted in the chute.
A common problem with such arrangements is that the relatively tall descending column of the refuse tends to pack in the chute, forming a plug of compressed refuse which becomes increasingly incapable of moving downwardly in the chute towards the furnace. Such a situation is especially likely to occur if among the refuse there happen to be a few bulky items. In this case these items may only partially block the chute but the incoming additional refuse will block the remainder of the chute cross-section and the resulting plug will become increasing compacted due to the pressure of still further refuse arriving through the inlet of such an arrangement.
The known charging devices do not provide any means for preventing development of such a plug or for preventing the compacting of the refuse.
It is to be understood in this context that providing only one wall of the chute with the stationary elements (see, for example, U.S. Pat. No. 3,696,951) will not prevent the development of such a plug.
It is also necessary to emphasize most strongly that even in prior-art instances where tearing-open of refuse bags is accomplished, it is nevertheless desired to further compact the liberated refuse. This is done in instances where dense packing of a space with refuse is desired. Of course, under such circumstances the compacted refuse--even though liberated from the bags--will burn only very poorly, if at all because, contrary to the invention, it will not be loosened up.